Walking mechanism for dragline excavators and the like



Feb. 3, 1970 WALKING MECHANISM Filed Dec. 26, 196'? E; c. WILSON3,493,064 FOR DRAQLINE EXCA VATORS AND THE LIKE 2 Sheets-Sheet 1INVENTOR ELLIS C. WILSON ATTORNEY Feb. 3, 1970 E. c. WILSON WALKINGMECHANISM FOR DRAGLINE EXCAVATORS AND THE LIKE Filed Dec. 26, 1967 '2Sheets-Sheet 2 I 1 I I I J Ill! U IIIT lllul INVENTOR ELLIS c. WILSON nATTORNEY United States Patent 3,493,064 WALKTNG MECHANISM FOR DRAGLINEEXCAVATORS AND THE LIKE Eliis C. Wilson, South Milwaukee, Wis., assignorto Bucyrus-Erie Company, South Milwaukee, Wis.,

a corporation of Delaware Filed Dec. 26, 1967, Ser. No. 693,204 Int. Cl.B62d 57/02, 51/06 US. Cl. 180-8 6 Claims ABSTRACT OF THE DISCLOSURE Thisdisclosure relates to a walking dragline of the type having walkingshoes on opposite sides of the machine which have a slide and slidewayconnection with the machine to allow for relative longitudinal movementduring a stepping action. According to the invention, the slideways onthe walking shoes are pivotally mounted to allow for rotation of themachine relative to the walking shoes to compensate for uneven groundconditions; and spring biased equalizer bars are provided on the shoesand engage the slideways to urge the shoes toward aligned positionsparallel to the machine.

This invention relates to a walking mechanism for dragline excavatorsand the like. More particularly, it resides in an improved walkingmechanism of the type where there is a slide and slideway connectionbetween a walking shoe and the machine, the primary improvement residingin mounting the slideway pivotally on the shoe to compensate for unevenground conditions.

A walking dragline usually has two shoes or sets of shoes on oppositesides of the main frame of the machine. When the machine is walking overuneven terrain, one shoe may contact the ground before the other. Evenon fiat surfaces, one shoe may be on firmer ground than the other shoe.Whenever the machine encounters such uneven conditions, there is atendency for the machine to rotate relative to one or both shoes. If themechanical connection between the machine and shoes does not allow forat least some relative rotation, the walking mechanism or the entiremachine will be subjected to severe torsional and bending forces andstresses which can result in serious damage or destruction. This problemexists in all machines of this general type, but is particularly seriousin extremely large and heavy machines. The machine disclosed therein,for example, has a working weight of approximately million pounds, andis equipped with 21 2'20 yard bucket and a boom in excess of 300 feet inlength. The stresses which might be encountered in moving a machine ofsuch proportions are enormous. Further, with a machine of this size theshoes are spaced so far apart that the likelihood of encountering unevenground conditions is quite great.

The walking mechanism described in US. Patent No. 3,265,145 to Beitzelprovides one workable solution to the problem of relative rotation. Themachine therein described is provided with walking shoes havingslideways rigidly mounted thereon, and slides on the machine properwhich are slidably received in the slideways. To compensate for groundirregularities, the slideways are constructed so as to provide a loosefit for the slides and this allows for lateral, angular rotation of theshoes with respect to the machine. It is also important to provide ameans for aligning the shoes prior to the beginning of a walking step,however, and to accomplish this, the Beitzel patent calls for slidewayswhich are tapered at one end, the slides being intended to be in thenarrowest part of the slideway just prior to the beginning of a stepwhen the shoes are still off the ground. Although the "ice Beitzelstructure is quite satisfactory, for various reasons it has been foundthat as a practical matter the lateral, angular rotation of the shoes ineither direction is limited to about 2". There are times when thisdegree of rotation is not enough, and it becomes necessary to providefor considerably greater rotation of the shoes. Further, where there areuneven ground conditions, it is possible with the tapered slideway forthe slide to still be in the narrowed part of the slideway after thebeginning of a walking step when the shoes are on the ground and weightis being put on them. In this case there is no room for relativerotation when it is most needed.

SUMMARY OF THE INVENTION In accordance with this invention, an improvedwalking mechanism for a dragline excavator is provided which includes awalking shoe capable of greatly increased lateral, angular rotation ineither direction with respect to the machine proper. This isaccomplished primarily by providing a pivotally mounted slideway on thewalking shoe.

It is the general object of this invention to provide an improvedwalking mechanism which includes such a pivotal slideway to provide forincreased rotatability. In

the particular embodiment shown, for example, the walking shoe iscapable of up to as much as 6 to 8 lateral, angular rotation in eitherdirection.

It is another object of this invention to provide an improved walkingmechanism which includes means for aligning the walking shoe withrespect to the machine at the beginning of a walking step.

It is still another object of the invention to provide a walkingmechanism having the foregoing advantages which is adaptable for use invarious types of walking machines.

It is still another object of the invention to provide an improvedmechanism which has the several cited features and advantages which isquite strong and readily adaptable to very large machines while stillbeing relatively simple and inexpensive to manufacture and maintain.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a somewhat schematic sideview in elevation showing a walking dragline excavator provided with awalking mechanism constituting a preferred embodiment of the invention,

FIG. 2 is an enlarged fragmentary top view through the plane 22 shown inFIG. 3, with parts shown broken away and in cross-section, furtherillustrating the walking mechanism of FIG. 1,

FIG. 3 is an enlarged fragmentary side view, with parts shown brokenaway and in cross-section, taken in the plane 3-3 shown in FIG. 2, and

FIG. 4 is an enlarged fragmentary end view taken in the plane 44 shownin FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT The dragline excavator shown inFIG. 1 is generally conventional and, for this reason and since thewalking mechanism of this invention is equally useful for other types ofmachines, is shown somewhat schematically and will be described onlybriefly. It includes, in general, a main or revolving frame 1 which isrevolvably mounted on a central supporting base or tub 2 and whichsupports a main boom 3 and usual appurtenant elements. A pair ofidentical walking shoes 4, only one of which can be seen, are disposedalongside the frame 1 and base 2 on opposite sides and are connected tothe frame 1 as will be described to be revolvable with it.

The connections between the frame 1 and shoes 4 constitute the walkingmechanisms, which are generally as shown and described in the said US.Patent No. 3,265,-

145. Again, however, only one set of connections or mechanism can beseen and will be described, but the mechanism on the other side of themachine is the same.

The walking mechanisms are driven by means of a shaft 5 which extendsoutwardly on both sides of the frame 1 and is driven by suitable motors(not shown). Each walking mechanism includes a circular driving disc 6eccentrically mounted on the shaft 5 and a walking frame designatedgenerally by the reference numeral 7 which is rotatably mounted on thedisc 6. The walking frame 7 includes an upper part 8, which actuallyreceives the disc 6, and a lower part 9, with a hinge connection 10therebetween. The lower part 9 is provided with laterally extendingflanges 11 to have an inverted T-configura tion, and serves as a slideas will be described.

A longitudinally extending slideway designated generally by thereference numeral 12 is provided on the flat upper surface of the shoe4, and slidably receives the slide part 9 of the walking frame 7. In theembodiment shown, the slideway 12 is of unitary construction andincludes a flat base portion 13 against the shoe 4 and opposite, facingangle portions 14 which overhang the slide flanges 11. The slideway,could, of course, also be made up of separate parts bolted or otherwiseconnected together.

A rigid link 15 has one end pivotally connected to the shoe 4 at a point16. The other end of the link 15 is pivotally connected to the disc 6 ata point 17 that is generally diametrically opposite from the shaft 5.

The operation of the walking mechanisms is as described in the aforesaidBeitzel patent. Rotation of the shaft 5 causes the frame 7 to be movedin what would be a circular path were the shoe 4 suspended in space. Atthe same time, the link 15 causes the shoe 4 to slide forwardly andrearwardly with respect to the frame 7, this motion being additive togive a resultant thoretical elliptical path to the shoe 4. In actualoperation, the shoe 4 is moved forwardly and downwardly until itcontacts the ground, and further rotation of the shaft 5 causes theleading edge of the tub 2 to be lifted and the machine proper to bemoved in the same direction as the shoe. The tub 2 is then lowered andthe shoe 4 picked upwardly and moved forwardly again. The net result ofrepeated rotations is a stepping type of action in which the machinemoves in a direction away from the boom 3, or to the left as seen inFIG. 1.

A large circular pivot pin 18, seen most clearly in FIG. 3, is fixed tothe underside of the slideway base portion 13, at a suitable point aswill be described, and is received in a circular opening 19, which isprovided with a suitable bearing surface, in the top of the shoe 4, sothat the entire slideway 12 is pivotally mounted on the shoe 4 to bemovable in a horizontal plane. A split retaining collar 20 received inan annular recess 21 near the outer end of the pin 18 and disposed in anenlarged chamber 22 below the opening 19 holds the slideway 12 againstvertical movement.

The ends of the slideway base portion 13 extend beyond the angleportions 14 to define toe portions 23 which are generally arcuate. Aspaced set of retaining blocks 24 are rigidly mounted on the top of theshoe 4 at either end of the slideway 12 and include lip portions 25which overhang the toe portions 23 to further hold the slideway 12against vertical movement off the shoe 4.

It will be appreciated that the pivotal mounting of the slideway 12allows, in effect, for relative rotation between the machine proper andthe shoes 4 in the event of uneven ground conditions. In the embodimentshown, up to 6 to 8 of rotation is possible, which represents asubstantial improvement over known prior arrangements. The hingeconnection 10 is also helpful in the event of uneven ground conditionssince it provides for movement of the shoes in a vertical planetransverse to the line of movement of the machine.

In the embodiment shown, the pin 18 is approximately at the longitudinalcenter of the slideway base 13. The

location of the pivot pin 18 with respect to the slide 9 and disc 6constantly changes during walking since the shoe 4 is constantly movingwith respect to the frame 7. To insure maximum effectiveness, the pin 18should be located so that it is approximately directly under the centerline of the disc 6 when the shoe 4 is placed on the ground at thebeginning of a step, or in other words at about the time when the tub 2begins to be raised.

As can be seen in FIGS. 2 and 3, the right-hand toe portion 23 of eachslideway 12 is provided with cast teeth 26. The teeth 26 mesh with arack segment 27 at one end of a lever arm 28 which has its other endfixedly connected by means of a vertical pin 29 to an equalizer bar 30disposed in a cavity 31 in the shoe 4. Rods 32 are fastened to each endof the bar 30, and constant biasing forces of equal magnitude areapplied to the rods 32 by means of springs 33 which operate betweenbrackets 34 in the shoe 4 and retainers 35 fixed to the rods 32. Theseelements constitute an aligning means which exerts a constant forceresisting the relative pivotal movement between the shoe 4 and slideway12 in either direction. Thus, the shoe 4 is urged toward a parallelrelationship with the slideway 12, the slide 9, the frame 7 and the mainframe 1, the two shoes 4 also being urged toward a parallel relationshipwith one another.

The alignment provided by the arm 28 and bar 30 and their associatedelements insures that the shoes 4 will be properly positioned at thebeginning of each step. The aligning elements are effective only whenthe shoe 4 is raised ofl? the ground, however, and are overridden whenthe machine proper is being lifted or moved. They do not, therefore,interfere with the desired compensating pivotal movement of the slideway12.

Thus, the embodiment of the invention shown and described hereinprovides an improved walking mechanism which provides for substantiallyincreased rotatability of the shoes 4. It will be obvious that thearrangement shown is relatively simple and easily adaptable to even verylarge machines.

Although a preferred embodiment of the invention has been shown, it willbe obvious that various modifications are possible without departurefrom the spirit of the invention. The invention is of course notnecessarily limited to dragline excavators, and may be useful in othertypes of walking machines. Nor is the invention limited to theparticular basic type of walking mechanism shown. the copendingapplication of Kraschnewski et al. Ser. No. 506,207, filed Nov. 3, 1965,and noW Patent No. 3,375,892 for example, shows a walking arrangementinvolving vertical and horizontal hydraulic cylinders to effect thedesired motion. The Kraschnewski et a1, arrangement also includes aslide and slideway connection between walking shoes and a machine andthe pivotal slideway herein could be advantageously incorporatedtherein.

Further, changes could be made in the specfic embodiment shown. Theparticular slide and slideway arrangement in which the slide 9 has aninverted T-configuration and the slideway 12 has the overhanging angleportions 14 is not critical; and a reverse arrangement could be usedwith the slideway having an upright T-configuration and the slide havinginwardly extending flanges under the crossbar portion thereof. Otheraligning arrangements for the shoes 4 could also be provided, or theparticular arrangement shown could be provided at both ends of eachslideway 12.

What is claimed is:

1. In a walking mechanism for a dragline excavator and the like having arevolving frame, a slide operatively connected to the revolving frame, ashoe alongside the revolving frame, and a slideway on the shoe thatslidably receives the slide to allow for relative longitudinal movementbetween the shoe and the revolving frame,

the improvement wherein the slideway is pivotally mounted on the shoe tobe movable in a horizontal plane.

2. The walking mechanism of claim 1 wherein the slideway comprises abase portion and there is a pivot pin attached to the underside of thebase portion which is received in the shoe to pivotally mount theslideway thereon.

3. The walking mechanism of claim 1 wherein the slideway has a toeportion at each end thereof; and there is a spaced set of facingretaining blocks mounted on the shoe, said blocks overhanging respectivetoe portions of the slideway.

4. The walking mechanism of claim 1 which includes means for aligningthe shoe with respect to the slideway prior to the beginning of awalking step.

5. The Walking mechanism of claim 4 wherein the aligning means comprisesbias means operative between the shoe and slideway to exert a constantforce resisting relative pivotal movement in either direction.

6. The Walking mechanism of claim 5 wherein there are teeth provided onat least a portion of at least one of the toe portions; and there is alever arm having a rack segment at one end which meshes with said teeth;and there is an equalizer bar, the other end of the lever arm beingfixedly connected to the equalizer bar intermediate the ends of the bar;and the bias means acts against the ends of the bar.

References Cited UNITED STATES PATENTS 2,399,375 4/ 1946 Mullins.2,399,417 4/1946 Wilson et al. 3,265,145 8/1966 Beitzel. 3,375,892 4/196 8 Kraschnewski.

LEO FRIAGLIA, Primary Examiner

